Gb Interface Link

Description

The GbLink is a managed object defined in the Generic Network Resources NRM of 3GPP TS 28.703. It represents a Gb interface link, which is the interface between a GERAN (GSM/EDGE Radio Access Network) and a GPRS core network node, specifically the SGSN (Serving GPRS Support Node). The Gb interface carries packet-switched user data and control signaling for GPRS and EDGE services. In the 3GPP management architecture, the GbLink object allows the network management system to model, configure, and monitor the Gb interface links within the network. It is derived from the GenericNetworkResourcesNRMDefs::ManagedFunction base class, inheriting common attributes such as identifier, administrative state, and operational state.

The Gb interface itself is a standardized interface that connects the Base Station Subsystem (BSS) to the GPRS core network. It supports the transfer of LLC (Logical Link Control) PDUs between the mobile station and the SGSN, as well as the signaling required for mobility management, session management, and radio resource management. The GbLink managed object represents a specific link or a set of links that constitute the Gb interface. It includes attributes that describe the link's configuration, such as the link identifier, the endpoints (e.g., BSS and SGSN), the protocol profiles (e.g., Frame Relay, IP), and the capacity parameters. The object also supports operations for fault management, configuration management, and performance management, as defined in the IRP specifications.

The GbLink is defined in TS 28.703, which specifies the Generic Network Resources NRM for GERAN and GPRS. The companion specification TS 32.636 defines the corresponding IRP information service, which specifies the operations that can be performed on the GbLink object. These operations include creating, deleting, and modifying GbLink instances, as well as retrieving their attributes and status. The management system uses these operations to configure the Gb interface, monitor its performance, and detect faults.

In terms of architecture, the GbLink object is typically instantiated under a ManagedElement that represents a BSS or an SGSN. It may be associated with other objects such as a GbLinkSet or a GbInterface object that groups multiple links. The GbLink object also supports the concept of a 'generic' link, meaning it can represent a link without requiring full details of the underlying transport technology. This is useful in multi-vendor environments where the transport technology may vary. The object's attributes include the link's operational state, which indicates whether the link is currently active, and the administrative state, which allows the operator to enable or disable the link.

From a practical standpoint, the GbLink is used in the management of GPRS and EDGE networks, which are still widely deployed for IoT and legacy services. It enables operators to manage the Gb interface efficiently, ensuring that packet-switched services are delivered reliably. The object also plays a role in the transition to IP-based transport, as it can model Gb over IP links. As networks evolve towards 5G, the Gb interface remains relevant for legacy devices, and the GbLink object continues to be used in management systems.

Purpose & Motivation

The GbLink managed object exists to provide a standardized way to manage the Gb interface in GERAN and GPRS networks. The Gb interface is critical for delivering packet-switched services to mobile users, and its management is essential for ensuring service quality and network reliability. Before the introduction of the Generic Network Resources NRM, the management of Gb links was often vendor-specific, leading to interoperability challenges and increased operational costs. The GbLink object addresses this by providing a standardized representation that can be used across different vendors' equipment.

The GbLink object also solves the problem of managing the Gb interface in multi-vendor and multi-technology environments. In a typical GPRS network, the BSS and SGSN may be from different vendors, and the transport technology may vary (e.g., Frame Relay, IP). The GbLink object abstracts these details, allowing the management system to configure and monitor the link without needing to know the specifics of the underlying transport. This abstraction simplifies management and reduces the risk of configuration errors.

Historically, the Gb interface was introduced with GPRS in the late 1990s. As GPRS evolved to EDGE and later to 3G, the Gb interface continued to be used. The need for standardized management became apparent as networks grew in size and complexity. The Generic Network Resources NRM, introduced in Release 10, provided a unified framework for managing various network resources, including the Gb interface. The GbLink object is a key part of this framework, enabling operators to manage the Gb interface efficiently and consistently.